• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.2
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• pp.84-90
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• 2005

The effects of UV-B radiation on the seedling growth, carbohydrate metabolism and antioxidants activities of rice (Oryza sativa L.) were investigated under environmentally controlled chamber. Supplementary UV­B radiation reduced dry matter as well as leaf area, there­fore, relative growth rates (RGR) of seedlings were decreased by up to half compared to control. Photosynthetic products such as soluble sugars and starch were rapidly and significantly reduced by within 1 day of enhanced UV-B radiation due to the inhibition and degradation of photosynthetic processes and thylakoid membrane integrity. In our study, nonstructural carbohydrate levels were proved to be a main indicator on UV-B­induced stress. The behavior of SOD, CAT, APX and POD activities was monitored in the leaves of rice seedlings subjected to UV-B radiation. Under UV-B treatments, SOD activity was initially increased, whereas CAT and POD activities were slowly and slightly increased. However, APX activity showed no presumable results with an increase of UV-B dose. In leaves of rice seedlings, supplementary UV-B radiation caused an increase in free putrescine and spermidine, however spermine remained unaltered, although 24-hrs UV-B treatment slightly increased. This result presumes that an excess UV-B dose may induce ethylene biosynthesis (senescence) rather than polyamine biosynthesis (defense).

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.2
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• pp.110-115
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• 2004

Rice (Oryza sativa L.) plants were cultivated to examine changes in antioxidative defence mechanism induced by elevated ozone levels. Catalase activities in tolerant Jinpumbyeo and susceptible Chucheongbyeo under ozone fumigation were reduced at 5 hrs and 3 hrs after ozone fumigation, respectively. With the increased ozone supply, peroxidase activity in Jinpumbyeo was steadily enhanced whereas in Chucheongbyeo it was not changed. Four SOD-isozymes were detected by NBT staining of native-PAGE. Two isozymes of them were obviously induced by ozone supply, particularly in Jinpumbyeo. The continuous ozone fumigation increased remarkably putrescine levels in leaves whereas it did not affect the levels of spermidine and spermine. In this study, it was implied that ozone in cell inhibits strongly diamine oxidase and thus promotes ethylene biosynthesis which will cause the senescence in rice plants.

• Biomaterials Research
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• v.22 no.4
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• pp.328-336
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• 2018

Background: Biogenic fabrication of silver nanoparticles from naturally occurring biomaterials provides an alternative, eco-friendly and cost-effective means of obtaining nanoparticles. It is a favourite pursuit of all scientists and has gained popularity because it prevents the environment from pollution. Our main objective to take up this project is to fabricate silver nanoparticles from lichen, Usnea longissima and explore their properties. In the present study, we report a benign method of biosynthesis of silver nanoparticles from aqueous-ethanolic extract of Usnea longissima and their characterization by ultraviolet-visible (UV-vis), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analyses. Silver nanoparticles thus obtained were tested for antimicrobial activity against gram positive bacteria and gram negative bacteria. Results: Formation of silver nanoparticles was confirmed by the appearance of an absorption band at 400 nm in the UV-vis spectrum of the colloidal solution containing both the nanoparticles and U. longissima extract. Poly(ethylene glycol) coated silver nanoparticles showed additional absorption peaks at 424 and 450 nm. FTIR spectrum showed the involvement of amines, usnic acids, phenols, aldehydes and ketones in the reduction of silver ions to silver nanoparticles. Morphological studies showed three types of nanoparticles with an abundance of spherical shaped silver nanoparticles of 9.40-11.23 nm. Their average hydrodynamic diameter is 437.1 nm. Results of in vitro antibacterial activity of silver nanoparticles against Staphylococcus aureus, Streptococcus mutans, Streptococcus pyrogenes, Streptococcus viridans, Corynebacterium xerosis, Corynebacterium diphtheriae (gram positive bacteria) and Escherichia coli, Klebsiella pneuomoniae and Pseudomonas aeruginosa (gram negative bacteria) showed that it was effective against tested bacterial strains. However, S. mutans, C. diphtheriae and P. aeruginosa were resistant to silver nanoparticles. Conclusion: Lichens are rarely exploited for the fabrication of silver nanoparticles. In the present work the lichen acts as reducing as well as capping agent. They can therefore, be used to synthesize metal nanoparticles and their size may be controlled by monitoring the concentration of extract and metal ions. Since they are antibacterial they may be used for the treatment of bacterial infections in man and animal. They can also be used in purification of water, in soaps and medicine. Their sustained release may be achieved by coating them with a suitable polymer. Silver nanoparticles fabricated from edible U. longissima are free from toxic chemicals and therefore they can be safely used in medicine and medical devices. These silver nanoparticles were stable for weeks therefore they can be stored for longer duration of time without decomposition.

• Journal of Microbiology and Biotechnology
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• v.33 no.4
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• pp.552-558
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• 2023

Levulinic acid (LA) is a valuable chemical used in fuel additives, fragrances, and polymers. In this study, we proposed possible biosynthetic pathways for LA production from lignin and poly(ethylene terephthalate). We also created a genetically encoded biosensor responsive to LA, which can be used for screening and evolving the LA biosynthesis pathway genes, by employing an LvaR transcriptional regulator of Pseudomonas putida KT2440 to express a fluorescent reporter gene. The LvaR regulator senses LA as a cognate ligand. The LA biosensor was first examined in an Escherichia coli strain and was found to be non-functional. When the host of the LA biosensor was switched from E. coli to P. putida KT2440, the LA biosensor showed a linear correlation between fluorescence intensity and LA concentration in the range of 0.156-10 mM LA. In addition, we determined that 0.156 mM LA was the limit of LA detection in P. putida KT2440 harboring an LA-responsive biosensor. The maximal fluorescence increase was 12.3-fold in the presence of 10 mM LA compared to that in the absence of LA. The individual cell responses to LA concentrations reflected the population-averaged responses, which enabled high-throughput screening of enzymes and metabolic pathways involved in LA biosynthesis and sustainable production of LA in engineered microbes.

• FLOWER RESEARCH JOURNAL
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• v.19 no.3
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• pp.139-143
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• 2011

This research was conducted to figure out the effect of 1-methylcyclopropene, one of inhibitors of ethylene on the vase life of cut alstroemeria 'Alpine', snapdragon 'Fuji no Yuki', dahlia 'Toast, and lily 'Georgia'. Four kinds of cut flowers were treated with 250, 500, and 750 ppb of 1-MCP respectively for 12 hours. In case of cut alstroemeria, no significant difference was found between the untreated control and the treated ones in the days to flowering. The vase life in the treated ones, however, was extended for over two days, and the treated one with 250 ppb had the longest record with 17.1 days. In every treated ones of cut snapdragon, the remaining florets was more than that of the untreated control. The vase life showed, however, no difference. With the 1-MCP treatment, the vase life of cut dahlia was longer about two days than that of the untreated control. However, water uptake showed the opposite result. The vase life of cut lily showed no significant differences in all treatments. In case of water absorption, the treated one with 750 ppb uptaken more water by 3 ml.

• Korean Journal of Breeding Science
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• v.42 no.5
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• pp.565-573
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• 2010

Thinning of apple fruitlets is one of the most laborious and important works for the improvement of fruit quality and for the promotion of sufficient flower bud formation to prevent alternate bearing in commercial cultivars. Lateral fruits of self-thinning apple cultivars fall naturally within 30 days after full bloom and only central fruit remains to mature. Differences of gene expression between central fruit and lateral fruit were investigated by differential display (DD) PCR. Partial cDNAs of 30 clones from the central fruit and 24 clones from the lateral fruit were selected for nucleotide sequence determination and homology searches. The levels of transcripts coding for proteins involved in pathogenesis related proteins, senescence, temperature stress, protein degradation, fruit browning, sorbitol metabolism were significantly higher in pedicels of lateral fruit than in pedicels of central fruit. On the other hand, the up-regulation of proteins involved in anthocyanin and flavanol biosynthesis and ethylene synthesis were observed in pedicels of central fruit. In Real time PCR analysis, cytochrome P450 gene was confirmed as showing a higher expression level in lateral fruit than in central fruit. The results of this study indicate that differentially expressed genes are related to self-thinning characteristics in apple tree.

• BMB Reports
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• v.37 no.3
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• pp.343-350
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• 2004

A cDNA clone for a salicylic acid-induced gene in Chinese cabbage (Brassica rapa subsp. pekinensis) was isolated and characterized. The cabbage gene encoding a protein of 392 amino acids contained a tandem array of two thiJ-like sequences. ThiJ is a thiamin biosynthesis enzyme that catalyzes the phosphorylation of hydroxymethylpyrimidine (HMP) to HMP monophosphate. Although the cabbage gene shows a similarity to bacterial thiJ genes, it also shares a similarity with the human DJ-1, a multifunctional protein that is involved in transcription regulation, male fertility, and parkinsonism. The cabbage thiJ-like gene is strongly induced by salicylic acid and a nonhost pathogen, Pseudomonas syringae pv. tomato, which elicits a hypersensitive response in Chinese cabbage. Treatment of the cabbage leaves with BTH, methyl jasmonate, or ethephon showed that the cabbage thiJ-like gene expression is also strongly induced by BTH, but not by methyl jasmonate or ethylene. This indicates that the cabbage gene is activated via a salicylic acid-dependent signaling pathway. Examination of the tissue-specific expression revealed that the induction of the cabbage gene expression by BTH occurs in the leaf, stem, and floral tissues but not in the root.

• Horticultural Science & Technology
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• v.30 no.6
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• pp.734-742
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• 2012

To compare RNA interference-mediated gene silencing technique and T-DNA integration for gene function analysis in Chinese cabbage, BrSAMS-knockout (KO) line and BrSAMS-knockdown (KD) line were used. The KO line had lost the function of a Brassica rapa S-adenosylmethionine synthetase (BrSAMS) gene by T-DNA insertion and the KD line had shown down-regulated BrSAMS genes' expression by dsRNA cleavage. From microarray results of the KO and KD lines, genes linked to SAMS such as sterol, sucrose, homogalacturonan biosynthesis and glutaredoxin-related protein, serine/threonine protein kinase, and gibberellin-responsive protein showed distinct differences in their expression levels. Even though one BrSAMS gene in the KO line was broken by T-DNA insertion, gene expression pattern of that line did not show remarkable differences compared to wild type control. However, the KD line obtained by RNAi technique showed prominent difference in its gene expression. Besides, change of polyamine and ethylene synthesis genes directly associated with BrSAMS was displayed much more in the KD line. In the microarray analysis of the KO line, BrSAMS function could not be clearly defined because of BrSAMS redundancy due to the genome triplication events in Brassicaceae. In conclusion, we supposed that gene knock-down method by RNAi silencing is more effective than knock-out method by T-DNA insertion for gene function analysis of polyploidy crops such as Chinese cabbage.

• Molecules and Cells
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• v.26 no.6
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• pp.536-547
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• 2008

Anthocyanidin synthase (ANS, leucoanthocyanidin oxygenase), a 2-oxoglutarate iron-dependent oxygenase, catalyzed the penultimate step in the biosynthesis of the anthocyanin class of flavonoids, from the colorless leucoanthocyanidins to the colored anthocyanidins. The full-length cDNA and genomic DNA sequences of ANS gene (designated as GbANS) were isolated from Ginkgo biloba for the first time. The full-length cDNA of GbANS contained a 1062-bp open reading frame (ORF) encoding a 354-amino-acid protein. The genomic DNA analysis showed that GbANS gene had three exons and two introns. The deduced GbANS protein showed high identities to other plant ANSs. The conserved amino acids (H-X-D) ligating ferrous iron and residues (R-X-S) participating in 2-oxoglutarate binding were found in GbANS at the similar positions like other ANSs. Southern blot analysis indicated that GbANS belonged to a multi-gene family. The expression analysis by real-time PCR showed that GbANS expressed in a tissue-specific manner in G. biloba. GbANS was also found to be up-regulated by all of the six tested abiotic stresses, UV-B, abscisic acid, sucrose, salicylic acid, cold and ethylene, consistent with the promoter region analysis of GbANS. The recombinant protein was successfully expressed in E. coli strain with pET-28a vector. The in vitro enzyme activity assay by HPLC indicated that recombinant GbANS protein could catalyze the formation the cyanidin from leucocyanidin and conversion of dihydroquercetin to quercetin, suggesting GbANS is a bifunctional enzyme within the anthocyanidin and flavonol biosynthetic pathway.

• Journal of Plant Biotechnology
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• v.41 no.3
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• pp.159-167
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• 2014

In eukaryotes, proteins that are secreted into ER are post-translationally modified by N-glycosylation, the patterns of which are significantly different between plant and animal cells. Biotechnology industry has already produced a number of therapeutic glycoproteins in plant cells. However, the aberrant glycosylation of therapeutic recombinant proteins in plant systems can cause immune problems in humans. Therefore, it is important to develop strategies for producing non-glycosylated forms to preserve biological activity and native conformation by a peptide: N-glycanase (PNGase). In this study, we try to isolate PNGase T gene from tomato, which can use as a platform plant for biotechnology industry. We isolated a cDNA (GenBank Accession number KM401550) from tomato leaves with 1,767 bp, which encoded a polypeptide of 588 amino acids with a predicted molecular mass of 65.8 kDa. We also investigated the expression patterns of PNGase T during fruit ripening of tomato. The transcripts of PNGase T, which were constitutively induced in tomato fruit from green stage, were significantly increased and reached a peak at orange stage. After which, those transcripts were continuously reduced. The expression pattern of PNGase T was coincided well with transcripts profiles of metacaspase gene, LeMCA, and senescence-related gene members of ACC synthase, LeACS2, LeACS4, and LeACS6, for ethylene biosynthesis during fruit ripening. These results suggest that PNGase T is involved in a de-glycosylation process associated with senescence and fruit ripening.